NOISE POWER SPECTRA OF INDUCTIVELY-COUPLED PLASMA-MASS SPECTROMETRY USING A COOLED SPRAY CHAMBER

The influence of the spray chamber temperature and the related aerosol water loading on ArO+ as typical spectral interference in inductively coupled plasma mass spectrometry (ICP-MS) is studied. Therefore, the noise power spectra for the ArO+ have been measured by use of fast Fou rier transform (FFT) analysis. A Meinhard nebulizer and a GMK nebulize r were used in connection with a cooled spray chamber at a temperature of 5-25-degrees-C. It could be found that the relative standard devia tion of the analyte signal in ICP-MS was improved by cooling the spray chamber. The noise power spectra showed that especially the white noi se goes down when the spray chamber is cooled. The overall white noise with the GMK nebulizer is shown to be higher in the case of an Al2O3 slurry than in the case of an AlCl3 solution, containing both 400 mug/ ml Al. The pumping pulse rates are clearly visible in the noise amplit ude spectra, but their amplitudes decrease at the presence of an impac tor bead in the GMK nebulizer. Shifts of the noise band around 355 Hz were shown to occur as a result of the power level and the outer gas f low as well.